The invention relates to a battery cartridge housing a primary (nonrechargeable) electrochemical cell such as a primary lithium cell, which can be used in place of a rechargeable cartridge.
Digital cameras and camcorders and other digital imaging devices are becoming smaller in size. For example, camcorders which are only slightly larger than a person""s hand, are now available. Such devices typically are provided with a rechargeable battery cartridge or power pack such as a rechargeable lithium ion cartridge. The rechargeable cartridge has a housing designed to fit and lock in place within a receiving cavity within the imaging device to be powered. The negative and positive terminals on the cartridge housing are oriented to contact negative and positive contacts, respectively, within the device to be powered. The cartridge is normally designed to be removed from the device being powered so that it can be recharged and then reinserted or else it can be recharged while locked in place within the device. In earlier camcorders the rechargeable cartridge was typically of a prismatic or rectangular configuration occupying a significant volume. Such rechargeable packs are commercially available and are fairly large, for example, having a width of about 2 inches or larger and length of about 2 to 3 inches or greater. As the size of camcorders and digital cameras have become smaller, the rechargeable cartridge has also become much smaller, reflecting the need for smaller capacity battery cartridges.
To accommodate the smaller battery cartridge, designers have begun to employ small size rechargeable cylindrical cells, such as small cylindrical lithium ion cells, housed therein. Such small size rechargeable lithium ion cells, for example, could typically have a diameter of between about 15 and 18 mm and larger, for example up to about 32 mm and length between about 25 and 50 mm and greater, for example up to about 58 mm. As the imaging devices become even smaller such rechargeable cells could also become smaller. The lithium ion cell when fully charged has a nominal voltage of about 4.0 volts or somewhat greater and an average voltage during discharge of between about 3.6 volts. Such rechargeable cells are sealed within the cartridge housing and are not intended to be removed therefrom.
It would be a benefit to provide a nonrechargeble primary power source alternative to rechargeable battery cartridges for small size camcorders and digital cameras. The nonrechargeable power source could provide the user with an alternative to the rechargeable cartridge as it can be used as replacement for such rechargeable cartridge. The availability of such nonrechargeable power source could also provide the manufacturer of the small size imaging device the option of providing the nonrechargeable power source included with sale of the device, instead of providing a more expensive rechargeable cartridge therewith.
It is thus desired to provide a primary (nonrechargeable) battery cartridge for small size camcorders, digital cameras and other small size direct current powered electronic devices, wherein the primary cartridge has a voltage preferably about 3.0 volts and can be used interchangeably with a rechargeable cartridge of similar size.
It is desired to provide a primary battery cartridge for small size camcorders, digital cameras and other small size electronic devices, wherein primary cells, preferably primary cylindrical cells, can be inserted easily into the cartridge housing and easily removed therefrom when discharged.
A principal aspect of the invention is directed to providing a primary (nonrechargeable) battery cartridge that can be used as a primary power source or as a substitution for a rechargeable cartridge for powering small size digital imaging devices such as handheld camcorders or digital cameras. The term xe2x80x9cprimary cartridgexe2x80x9d or xe2x80x9cprimary cellxe2x80x9d or xe2x80x9cprimary batteryxe2x80x9d as used hereinafter shall be understood to mean a battery cartridge or electrochemical cell which is not intended to be rechargeable.
The primary (nonrechargeable) battery cartridge of the invention is characterized by having a housing body with an opening therein, preferably an elongated opening, of sufficient size to allow insertion of one or more cylindrical primary (nonrechargeable) cells into the housing interior. The opening is of sufficient size so that when the cell has been discharged, it can easily be removed from the housing and replaced with a fresh cell. The housing is desirably of a nonconductive material such as plastic which can be readily molded by injection or insert molding. The housing is preferably of a single piece integral construction. The housing has an elongated substantially cylindrical shape so that it can accommodate and hug at least a major portion of the surface one cylindrical primary cell placed therein with little, if any, wasted volume. The housing preferably avoids the need for hinged doors and removable covers and the like in order to gain access to the housing interior.
The cartridge housing preferably has a substantially cylindrical body which terminates in a pair of opposing end surfaces with a substantially cylindrical surface integrally formed therebetween. There is preferably an elongated opening taking the form of a cut out portion within the body of housing to allow easy insertion of one or more primary cells therethrough and into the housing interior. Such design avoids the need to have hinged doors and the like attached to the body or end of the housing which must be opened before the cell can be inserted within the housing. However, as an alternative, the housing could be provided with a hinged door, for example, at an end of the housing or as part of the housing body. Opening of such door could allow access to the housing interior and placement of one or more primary cell therein.
There are a pair of electrical contacts within the housing, formed of a strip of conductive metal such as copper or brass. One of said conductive contact strips is intended to contact the negative terminal and the other intended to contact the positive terminal of a cylindrical primary cell placed within the housing. Each of the conductive contact strips terminates in an exposed conductive portion which extends to the outside surface of the housing. One of the exposed conductive portions provides the negative and the other provides the positive terminal on the cartridge housing exterior (cartridge housing positive and negative terminals).
The battery cartridge preferably further comprises a disk within the cartridge housing interior. The disk is located between the opposing housing end surfaces and preferably oriented perpendicular to the housing central longitudinal axis. The disk has an opening therethrough. A metal contact strip can be held in place within the disk opening. Such metal contact strip contacts the positive terminal of a cell within the housing and is in electrical contact with the cartridge housing positive terminal.
When a primary cell is inserted into the cartridge housing, a primary battery cartridge is formed with the exposed negative contact on the housing exterior (cartridge housing negative terminal) in electrical contact with the cell""s negative terminal and the exposed positive contact on the housing exterior (cartridge housing positive terminal) in electrical contact with the cell""s positive terminal. The overall shape and size of the primary cartridge of the invention can be modified as needed to conform to the overall shape and size of a rechargeable cartridge intended for insertion into the receiving cavity of any specific small sized camcorder or handheld digital camera or other small direct current powered device.
In a specific aspect the cartridge housing of the invention can be of sufficient size to accommodate a cylindrical primary cell typically having a diameter of between about 15 and 18 mm and larger, for example up to about 32 mm and length between about 25 and 50 mm and greater, for example, up to about 58 mm. In a preferred embodiment the cartridge housing of the invention is of sufficient size to accommodate a primary cylindrical lithium cell of standard size designated in the art as a 123A size which corresponds to a cell of 15 mm diameter and 34 mm length. Such cells are characterized by having a lithium metal anode and manganese dioxide or lithiated manganese dioxide cathode and an operating voltage of about 3.0 volts. Alternatively, the cartridge housing of the invention can be sized to accommodate small sized primary lithium cells, for example a CR2 size cell which has a diameter of about 14 mm and length of about 26 mm. It will be appreciated that the housing size can be adjusted as required to house primary lithium cells of other cylindrical sizes either larger or smaller than the above two representative sizes.
In another specific aspect the cartridge housing of the invention can be designed to have an internal volume large enough to house two cylindrical lithium cells which are connected in parallel within the housing. Such cells are also easily inserted into the housing interior preferably through an integrally formed elongated opening in the housing body. The use of two or more primary cells connected in parallel extends the capacity of the cartridge. Alternatively, two or more primary cells could be inserted into the housing interior through an elongated opening in the cartridge housing and the cells connected in series within the cartridge housing to obtain a higher voltage. Although the cartridge housing described herein is intended in its preferred embodiment to house cylindrical primary cells, the concept of the invention extends to other primary cell shapes with the overall shape and size of the housing modified to accommodate such other shaped cells. For example, the cartridge housing of the invention overall shape and size could be modified to accommodate one or more prismatic or rectangular shaped primary cells or one or more button shaped primary cells or one or more elongated noncylindrical shaped primary cells.
In a specific aspect the cartridge housing comprises a partition disk having an opening therethrough. The disk is positioned within the housing interior and is preferably perpendicular to the cartridge housing central longitudinal axis. The disk can divide the housing interior into two compartments. The disk can have positioned in the opening therein a metal strip which is in electrical contact with the exposed cartridge housing positive terminal. A first primary cell can be placed into one of the compartments through an elongated opening in the housing body and a second primary cell can be placed into the other compartment through said same elongated opening in the housing body. The cells are aligned head to head with the cells positive terminals contacting opposite sides of said metal strip therebetween being held in place by said partition disk. Such metal strip thereby electrically connects each of the cell""s positive terminals to the cartridge housing positive terminal. Each of the cell""s negative terminals are electrically connected to the cartridge housing negative terminal. The two primary cell""s are thus connected in parallel. If the cell are primary lithium cells the cartridge voltage will be about 3.0 volts.